The entire disclosures of Japanese Patent application Nos. H11-202867 and H11-20268, both filed Jul. 15, 1999, inclusive of their specifications, claims and drawings are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a novel cutting tip used as a tool for a cutting process, and a cutting method using the novel cutting tip.
2. Description of the Related Art
When a cutting process is performed on a metallic material, the process is normally performed by setting a cutting tip in a machine tool, such as a lathe or the like, and by moving the cutting tip relative to the workpiece while keeping the cutting tip in contact with the workpiece.
Cutting tips vary in correspondence to the shapes of workpieces, desired shapes of cut, and the like. For example, there are cutting tips of various shapes, such as a triangular shape, a quadrangular shape, a rhombus shape, and the like.
As shown in FIG. 21, a conventional tip 9, regardless of what shape it has, has a cutting face 91 and a flank face 92, and a cutting edge 95 formed along a line of intersection between the cutting face 91 and the flank face 92. Normally, the cutting tip 9 is set in a shank 99 that holds the cutting tip.
At the time of cutting, the cutting tip 9 is normally placed in contact with a workpiece, with the cutting face 91 standing with respect to the surface of the workpiece, and then it is moved relative to the workpiece. As a result, swarf is separated from the surface of the workpiece, with the cutting edge 95 being a boundary, and it is scooped out onto the cutting face 91. Cutting processes for metallic materials achieve excellent dimensional precision, but cannot strengthen processed surfaces, unlike a process imparting plastic deformation. Therefore, various methods for strengthening a finished cut surface have been proposed.
For example, there is a method in which in a separate compression process, after the cutting process, the cut surface is pressed with a fillet tool or the like, thereby work-hardening the cut surface.
Japanese Utility Model Application Laid-Open No. HEI 7-20215, Japanese Utility Model Application Laid-Open No. SHO 63-116219, and like publications, have disclosed methods using a composite tool combining a cutting tool feature with a pressing tool feature. The use of such a tool makes it possible to perform successive cutting and compression processes using the same tool.
However, the above-described conventional cutting methods have the following problems.
In the method using a fillet tool or the like, the compression step needs to be separate from the cutting step, so that the overall process becomes complicated.
In the method using a composite tool combining a cutting tool feature with a pressing tool feature, the tool is limited to a specific purpose such as forming a hole, forming a flat surface, or the like. Therefore, the method is not easily applied to various different cutting processes.
The object of the present invention is to overcome the aforementioned problems. The invention is intended to provide a cutting tip that allows a compression process to be easily performed on a finished cut surface, and a cutting method using the cutting tip.
A first aspect of the invention provides a cutting tip having a cutting face and a flank face, wherein a compression-producing face for plastically deforming the workpiece is provided in at least a portion of an area between the cutting face and the flank face. The compression face intersects both the cutting face and a flank face at angles substantially less than 180 degrees, i.e. to define lines of intersection therewith.
The compression-producing face (hereinafter xe2x80x9ccompression facexe2x80x9d) is a face for plastically deforming a workpiece, as mentioned above. The expression xe2x80x9cplastic deformationxe2x80x9d as used herein refers to work-hardening involving dislocation.
The compression face is provided on at least a portion of the area between the cutting face and the flank face. Therefore, the compression face may be provided throughout the entire length of a boundary portion between the cutting face and the flank face or may be provided in a portion thereof or in a plurality of separate sites therein.
With the cutting tip provided with a compression face between the cutting face and the flank face, it is possible to produce plastic deformation of the workpiece simultaneously with the cutting process, in a single step, merely by cutting in substantially the same manner as a conventional method.
When cutting with the cutting tip of the invention, the cutting tip is brought into contact with a surface of a workpiece and moved relative thereto in a cutting direction, with the compression face of the cutting tip facing the surface of the workpiece and with the cutting face standing with respect to that surface. In this manner, first, a portion of the workpiece that contacts the cutting face is separated as swarf. A portion of the material of the workpiece facing the compression face is left as a work-hardened xe2x80x9cremainingxe2x80x9d portion. Then, as the relative movement of the cutting tip progresses, the cut surface left on the workpiece is pressed by the compression face and thereby undergoes plastic deformation and becomes work-hardened. Hence, a work-hardened portion strengthened by plastic deformation is formed on the cut-finished surface over which the compression face of the cutting tip has passed during the cutting process.
According to a second aspect of the invention, a cutting edge may be formed on an intersection line between the compression face and the cutting face. That is, if a clear cut edge is provided at the intersection line between compression face and the cutting face, the separation of swarf can be smoothly performed. Therefore, the subsequent compression of the remaining portion of the surface material by the compression face can also be smoothly performed.
The cutting edge is the starting point for separation of swarf.
According to a third aspect of the invention, the angle formed between the compression face and the cutting face is less than 125 degrees. If this angle is not less than 125 degrees, the intersection line between the compression face and the flank face may act as a cutting edge, thereby creating a problem of failing to properly separate swarf from the workpiece portion and a problem of failing to achieve work-hardening by plastic deformation.
According to a fourth aspect of the invention, the height of the intersection line between the compression face and the cutting face may be set in accordance with a desired amount of plastic deformation. That is, plastic deformation is produced in that portion of the workpiece facing the compression face. Therefore, by setting the height of the intersection line, the amount of plastic deformation produced in the workpiece material can be easily adjusted.
The xe2x80x9cheight of the intersection linexe2x80x9d can be expressed by, for example, the distance from the intersection line to the end of the compression face as viewed from the cutting face.
It is also possible to provide the compression face in the form of a curved surface whereby the intersection line is in the form of a curved line.
A fifth aspect of the invention provides a cutting method for cutting a workpiece by use of a cutting tip having a cutting face, a flank face, and a compression face provided between the cutting face and the flank face, and wherein that portion of the workpiece facing the cutting face is separated as swarf by relative movement of the cutting tip in a cutting direction while the compression face contacts a remaining portion of the workpiece facing the compression face to plastically deform that facing (remaining) portion by compression thereof.
In this cutting method, since a cutting tip having a compression face is used, compression, that is plastic deformation, is easily applied to a cut surface of a workpiece merely by performing a normal cutting operation, as described above. Therefore, a work-hardened portion can be formed on the cut surface of the workpiece, and the cut-finished surface can be easily strengthened.
A sixth aspect of the invention provides a finished workpiece having a cut-finished surface which has been work-hardened by plastic deformation caused by pressing with the compression face.
The formation of the finished cut surface of the workpiece is obtained by using the above-described special cutting tip. Therefore, it is possible to form a work-hardened portion on the cut-finished surface merely by performing a cutting operation substantially the same as a conventional method. Hence, there is no need to provide a separate, additional process step for strengthening the cut-finished surface after the cutting process step. Consequently, a finished workpiece having a strengthened cut surface can be provided at low cost.
Since the work-hardened portion is formed by plastic deformation by the compression face of the cutting tip, the work-hardened portion can be stably and uniformly formed as long as the cutting operating parameters are fixed.
Therefore, the finished workpiece in accordance with the invention is low-cost and has a uniformly strengthened cut-finished surface. Consequently, the durability of a machine constructed by using the finished workpiece as an element thereof is improved, and other applications for the finished workpiece are expanded.
A seventh aspect of the invention provides a cutting tip having a cutting face and a flank face and a corner portion, where a compression face for plastically deforming a workpiece is provided between the cutting face and the flank face. If there are a plurality of corner portions, one or more or all of the corner portions may be provided with compression faces in accordance with the intended application.
The compression face is a face for plastically deforming a workpiece, as mentioned above. The expression xe2x80x9cplastic deformationxe2x80x9d as used herein refers to work-hardening involving dislocation.
The operation and advantages of the invention will next be described.
As described above, the cutting tip of the invention has a compression face between the cutting face and the flank face in a corner portion. Therefore, using the cutting tip, it is possible to impart plastic deformation to a workpiece simultaneously with cutting thereof, merely by executing a cutting method that is substantially the same as a conventional method.
For cutting, the cutting tip""s corner portion having the compression face is brought into contact with a surface of a workpiece and the cutting tip is moved relative to the workpiece in a cutting direction, with the cutting face of the cutting tip standing with respect to the workpiece surface. Thereby, the portion of the workpiece that contacts the cutting face is separated as swarf. The portion of the workpiece facing the compression face becomes a work-hardened portion that remains on the workpiece.
Then, as the relative movement of the cutting tip progresses, the remaining portion left on the workpiece is pressed by the compression face and thereby. undergoes compression (or plastic deformation), and becomes work-hardened. Hence, a work-hardened portion strengthened by the plastic deformation is formed on the cut-finished surface over which the compression face of the cutting tip passes during the cutting process.
An eighth aspect of the invention provides a cutting tip having a cutting face and a flank face and two corner portions, wherein a compression face for plastically deforming a workpiece is provided between the cutting face and the flank face in at least one of the corner portions. In this eighth aspect, the cutting tip of the invention is a cutting tip for grooving. The use of the cutting tip of the invention make it possible to easily strengthen the bottom angle portions of a groove formed with the cutting tip.
That is, when a cutter of the invention carries a tip which forms a groove, the two corner portions of the cutting tip are brought into contact with a surface of a workpiece and the cutting tip is relatively moved in a cutting direction, with the cutting face of the cutting tip standing with respect to the surface of the workpiece, whereby that portion of the workpiece that contacts the cutting face is separated as swarf.
In cutting with a corner portion having a compression face, that portion of the workpiece material facing the cutting face is separated as swarf (as mentioned above), whereas that portion facing the compression face becomes a xe2x80x9cremaining portionxe2x80x9d that is left on the workpiece. Then, as the relative movement of the cutting tip progresses, the remaining portion left on the workpiece is pressed by the compression face and thereby undergoes plastic deformation, and becomes work-hardened. Hence, work-hardened portions are formed in the bottom angle portions of the groove through which the compression face passes during the cutting process.
Thus, if the cutting tip is used for cutting a groove, it is possible to easily strengthen bottom angle portions of the groove merely by performing a cutting operation, substantially the same as a conventional operation, without adding a separate process step.
Furthermore, according to a ninth aspect of the invention, a honing face may be formed on a cutting edge formed on an intersection line between the cutting face and the flank face, the angle formed between the compression face and the cutting face is smaller than the angle formed between the honing face and the cutting face, and the maximum width of the compression face viewed from the cutting face is greater than the maximum width of the honing face.
A cutting edge is formed on a intersection line between a cutting face and a flank face of a cutting tip, as described above. In many cases, a honing face is formed on the cutting edge by a honing process in order to prevent chipping of an angle portion (vertex portion) of the cutting edge. Although the honing face is provided between the cutting face and the flank face, similar to the compression face, the purpose of the honing face is different from that of the compression face, and the honing face provides substantially no compression of the cut-finished surface. However, if a compression face is provided so that the angle of the compression face with respect to the cutting face is smaller than the angle of the honing face with respect to the cutting face and so that the maximum width of the compression face is greater than the maximum width of the honing face, as described above, it becomes possible to easily work-harden the xe2x80x9cremainingxe2x80x9d portion of the material of the workpiece.
Furthermore, according to a tenth aspect of the invention, a cutting edge may be formed on an intersection line between the cutting face and the compression face. That is, if a clear cut edge is provided on the intersection line between the compression face and the cutting face, the separation of swarf from the remaining portion can be smoothly performed. Therefore, the subsequent compression of the remaining portion by the compression face can be smoothly performed.
xe2x80x9cCutting edgexe2x80x9d herein refers to an angle portion formed by intersecting faces of a cutting tip which, in cutting, is the starting point of separation of swarf.
According to an eleventh aspect of the invention, the line of intersection between the compression face and the cutting face is a straight line. In this case, the intersection line defines a constant amount of the remaining workpiece material pressed by the compression face, so that the amount of plastic deformation and the like can easily be set. Furthermore, it is also easy to form a compression face on the cutting tip. Of course, as previously noted, it is also possible to provide the compression face in the form of a curved face and the intersection line as a curved line.
In a twelfth aspect, the present invention provides a cutting method for cutting a workpiece using a cutting tip having a cutting face, a flank face and a corner portion, and a compression face provided between the cutting face and the flank face as a corner portion, and wherein that portion of the workpiece facing the cutting face is separated as swarf by relative movement of the cutting tip in a cutting direction while the compression face is in contact with the workpiece, and a remaining portion left in a position facing the compression face is plastically deformed by pressing the remaining portion with the compression face.
In this cutting method, since the cutting tip having the compression face is used, it is possible to easily cause plastic deformation of a cut surface of a workpiece merely by performing an ordinary cutting process, as described above. Therefore, a work-hardened portion can be formed on the cut surface of the workpiece, and the cut-finished surface can easily be strengthened.
A thirteenth aspect of the invention provides a cutting method for forming a groove in a workpiece using a cutting tip having a cutting face, a flank face and two corner portions, and a compression face between the cutting face and the flank face in at least one of the corner portions. In this method of cutting a groove, the workpiece material facing the cutting face is separated as swarf by relative movement of the cutting tip in a cutting direction while the corner portion having the compression face is in contact with the workpiece at a position corresponding to a bottom angle portion of the cut groove, and a remaining portion left in a position facing the compression face is plastically deformed by pressing with the compression face.
In this groove cutting method, since the cutting tip having the compression face is used, it is possible to easily cause plastic deformation in at least one of bottom angle portions of the cut groove merely by performing an ordinary cutting process, as described above. Therefore, a work-hardened portion can be formed in the at least one bottom angle portion of the groove of the workpiece, and the groove can easily be strengthened.
A fourteenth aspect of the invention provides an element having a cut-finished surface which has been subjected to a cutting process, wherein formation of the cut-finished surface is performed by using a cutting tip which has a cutting face, a flank face and a corner portion and has, between the cutting face and the flank face in the corner portion, a compression face for plastically deforming a workpiece, and wherein the cut-finished surface has a work-hardened portion formed by plastic deformation caused by pressing with the compression face.
The formation of the cut-finished surface of the workpiece is accomplished by using the above-described special cutting tip. Therefore, a work-hardened portion can be formed on the cut-finished surface merely by performing a cutting method substantially the same as a conventional method. Hence, since there is no need for a separate strengthening step after the cutting process, the finished element having a strengthened cut-finished surface can be provided at low cost.
Furthermore, since the work-hardened portion is formed by the compression face of the cutting tip, the work-hardened portion can be stably and uniformly formed as long as the cutting conditions remain fixed.
Therefore, the finished workpiece formed by the invention is low-cost and has a uniformly strengthened cut-finished surface. Hence, a machine constructed with the finished workpiece as an element thereof has improved durability, and the potential uses of the finished workpiece are expanded.
A fifteenth aspect of the invention provides a cutting-processed element having a groove formed by a cutting process, wherein formation of the groove is performed by using a cutting tip which has a cutting face, a flank face, two corner portions and, between the cutting face and the flank face in at least one of the corner portions, a compression face for plastically deforming the workpiece material, and wherein the at least one of the bottom angle portions of the groove is work-hardened by plastic deformation caused by pressing with the compression face.